Management of root-knot nematodes (Meloidogyne spp.,) using fungi that parasitize eggs of root-knot and cyst nematodes has been gaining popularity. Application of this fungus to plants that are poor host to root-knot nematodes has shown good results. This study was conducted to screen plants that support growth of Pochonia chlamydosporia on its rhizosphere. Seedlings of cabbage, sunhemp, maize, velvet bean, African marigold and tomato were planted in pots containing sterilized soil which had Pochonia chlamydosporia. Thirty days after planting, the fungal propagules in the soil and roots increased significantly (P<0.05) in all plants with the exception of velvet beans. Ninety days after planting, the counts of the fungal propagules taken from the soil were significant higher (P<0.05) in the rhizosphere where maize was planted than in other plants. This study concluded that maize is a promising rotational in system where P. chlamydosporia is used as a biocontrol agent.

Three foliar fungicides namely, Antracol, Kocide 101 and Folicur were evaluated for the control of Septoria leaf spot caused by S. vignicola V.G. Rao on cowpea [Vigna unguiculata (L.) Walp.] at two field sites in Kenya: Kabete and Katumani. The cowpea variety used was the high yielding Machakos 66 that was also susceptible to Septoria leaf spot. Reduction in disease incidence and severity of Septoria leaf spot on cowpea was obtained with the three fungicides. However, significant (P≤0.05) increase in seed yields was obtained when Kocide 101 and Antracol were applied to cowpea plants with the disease at Katumani. Folicur was found to be phytotoxic to cowpea plants and hence reduced plant dry weight and seed yield at both sites. Based on the cost-benefit analysis of the fungicides in the present study, Antracol and Kocide 101 are recommended for the control of Septoria leaf spot on high yielding cowpea varieties in arid and semi-arid areas. The Pearson correlation (r) between the disease incidence and seed yield was 0.75 (P=0.46), while that between disease severity and seed yield was 1.00 (P=0.01).

Field plots of sesame (Sesamum indicum) with six different levels of seed infection with Alternaria sesami were monitored for Alternaria leaf spot severity at Kibwezi, eastern Kenya. The aim of the study was to determine the effect of seed transmission of the pathogen on yield and tolerance level of the fungus in sesame seed. Increase in percentage leaf area diseased and percentage defoliation fitted the Gompertz model more closely than the logistic model. Areas under disease progress curves (AUDPC), infection and defoliation rates varied among the six infection levels. Disease severity increased with increase in seed infection and was least and most severe in plots established with seeds with 0 and 8% infection levels respectively. Yields ranged from 234.9 to 300.1 kg ha−1 compared with 312.5 kg ha−1 for the control, and losses due to seed infection ranged from 4% to 25%. Disease severity was negatively correlated with seed yield, 1000-seed weight and seeds per capsule. Alternaria leaf spot severity had a major effect on the seed weight component of yield. Tolerance level of A. sesami in sesame seed was determined to be less than 2%.

This article is about pyrethrum production in Kenya which is greatly constrained by a disease characterised by wilting and eventual death of pyrethrum plants. To date, Fusarium graminearum schwabe, F. solani (Mart.) Sacc., Rhizoctonia solani kuhn, Sclerotinia monor jagger, S. sclerotiorum (Lib) de Bary, and lesion nematodes (Pratylenchus spp.) have been associated with the wilt disease of pyrethrum. The study was carried out to determine the primary casual agent of the disease. Disease plant samples were collected from five pyrethrum growing areas, namely Kisii, Molo, Mwongoris, Sotik and Limuru for isolation and identification of pathogens associated with the disease.